ZyXEL Communications 645R-A Series User Manual

Prestige 645R-A Series User’s Guide 

PPPoE  

C-1 

An ADSL modem bridges a PPP session over Ethernet (PPP over Ethernet, RFC 2516) from your PC to an 
ATM PVC (Permanent Virtual Circuit) which connects to a xDSL Access Concentrator where the PPP 
session terminates (see the next figure).  One PVC can support any number of PPP sessions from your LAN. 
PPPoE provides access control and billing functionality in a manner similar to dial-up services using PPP. 

PPPoE offers the following benefits: 

1.  It provides you with a familiar dial-up networking (DUN) user interface. 

2.  It lessens the burden on the carriers of provisioning virtual circuits all the way to the ISP on multiple 

switches for thousands of users.  For GSTN (PSTN and ISDN), the switching fabric is already in place. 

3.  It allows the ISP to use the existing dial-up model to authenticate and (optionally) to provide 

differentiated services. 

The following diagram depicts a typical hardware configuration where the PCs use traditional dial-up 
networking.